Toner can be prepared by pulverization or polymerization. According to the pulverization method, toner is prepared by melting and mixing synthetic resins with pigments and, if required, other additives, pulverizing the mixture, and sorting particles until particles of a desired size are obtained. According to the polymerization method, a polymerizable monomer composition is manufactured by uniformly dissolving or dispersing various additives such as a pigment, a polymerization initiator and, if required, a cross-linking agent and an antistatic agent in a polymerizable monomer. Then, the polymerizable monomer composition is dispersed in an aqueous dispersive medium, which includes a dispersion stabilizer, using an agitator to shape minute liquid droplet particles. Subsequently, the temperature is increased and suspension polymerization is performed to obtain polymerized toner having colored polymer particles of a desired size.
Conventionally, toner used in an image forming apparatus is usually obtained using pulverization. According to the pulverization, the particle size, geometric size distribution, and structure of toner may not be precisely controlled, and thus major properties of toner such as charging properties, fixing properties, fluidity, or storage properties may not be independently designed.
Polymerized toner has been highlighted recently. The size of polymerized toner particles may be easier to control and a complex manufacturing process such as sorting may not be necessary. That is, when toner is prepared through polymerization, polymerized toner having a desired particle size and geometric size distribution may be obtained without pulverizing or sorting. As an example of polymerization, a method of preparing a toner using a metal salt, such as MgCl2 or NaCl, as an agglomerating agent may be used to uniformly control the particle size and shape of the toner. Furthermore, a method of controlling the structure of capsule type toner by controlling agglomeration of the toner may be used in order to increase durability, i.e., charging properties, and storage properties at high temperature.